1. Field of the Invention
This invention relates to a glass vessel edge chamfering method and apparatus wherein an edge such as a lip or a bottom edge of a glass vessel produced by press molding or blow molding is heated into a softened condition to round the edge in order to remove an angle from the edge.
2. Description of the Prior Art
A glass vessel molded by press molding such as, for example, a piece of glass tableware is liable to have an angle at a lip thereof which corresponds to a Joining line between a body die and a plunger ring of a molding machine. Therefore, after molding of the glass vessel, finishing processing called fire-polishing is normally performed wherein the lip of the glass vessel is heated with a flame of a burner into a softened condition to chamfer the same.
Various fire polishing methods are conventionally known. A popular conventional fire polishing method is to set a glass vessel in position below a ring-shaped burner and apply a flame from the ring-shaped burner to the entire circumference of the lip of the glass vessel to fire polish the entire lip at one time. Another popular conventional fire polishing method is to apply flame from a burner to a lip portion of a glass vessel while rotating the glass vessel at a position very near to the burner which is in the form of a straight pipe and is set in position to fire polish the edge of the glass vessel. A further fire polishing method is disclosed in Japanese Patent Publication Application No. 62-28096 wherein a lip of a glass vessel is fire polished with flame from a burner in the form of a straight pipe while cooling air is blown to the lip of the glass vessel to prevent possible deformation of the lip of the glass vessel by the fire-polishing.
The conventional fire polishing methods described above wherein flame from a burner is applied directly to the lip of a glass vessel to fire polish the lip have various associated problems as described below:
(1) Since the distance between the lip and flame is not fixed, irregular fire polishing may result. PA1 (2) Since the degree of fire polishing varies widely depending upon the intensity of the flame of the burner or the time over which the flame is applied to the lip, it is difficult to control heat energy. PA1 (3) Chamfering processing of a glass vessel having a deformed profile or local chamfering processing is not easy. PA1 (4) Since the thermal efficiency is generally low and the heating time for one glass vessel is several tens of seconds and longer, a great number of workpieces must be processed at a time in mass production, and consequently, the equipment for the fire polishing (chamfering) step is large in scale and expensive. PA1 (5) Radiation of a great amount of heat has a bad influence upon the operational environment therearound.